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By T. Ritzel

Predictive maintenance technologies including vibration analysis, tribology, infrared thermography, ultrasonic detection, and electrical measurements have been applied to large electric mining shovels at Cyprus Sierrita. The predictive program was initiated by Cyprus Sierrita and P&H Mining Equipment at the Cyprus Sierrita Mine in Tucson, Arizona during August of 1996 on the P&H model 2300 and 4100 electric shovels. The utilization of these technologies has shown the potential for improving electric mining shovel availability and minimizing maintenance costs. Predictive technologies provide the tools to assess machinery condition. Availability is enhanced by the condition based planning of component replacement. Maintenance costs are minimized by focusing resources through condition based prioritization.

Jan 1, 1997

By Danforth R. Hale

The pressure of military use of quartz resonators led to efforts to Grow high, grade quartz crystals in Germany and in Great Britain during 19)3-25, and was responsible for a series of U.S.A. Signal Corps contracts beginning in 1946 with the Clevite Corporation (as the former Brush Development Company), Bell Telephone Laboratories, Antich College, and others. The technique of growing crystals from the melt, such as KI, NaBr, was already commercially inuse Quartz could not be so grown, since its utility depends on the form stable below 573°C, and, even if it could be grown from an extraordinarily viscous melt, the higher form passing through this transition becomes twinned. Again, several crystals were being grown commercially from water solutions; quartz, however, is listed in the common literature as being insoluble in water. Fused quartz, or vitreous silica, was chosen as raw mater¬ial by the European experimenters because of its thermodynamically lesser stability than quartz, and various alkaline solutions were tried for the purpose of enhancing the solubility.

Jan 1, 1964

By D?Arcy R. George

A survey of the copper mining industry in Western United States revealed that uranium is almost universally present in the solutions resulting from leaching the waste ore dumps to recover copper. The U308 content ranges from about 2 to 15 ppm and a potential production of up to 1,000 tons of U3O8 per year is indicated. A six-week pilot plant test at the Bingham Canyon mine of Kennecott Copper Corporation showed that the uranium is readily recoverable by ion exchange techniques. The design of the new types of countercurrent ion exchange columns and operation of the pilot plant are described.

Jan 1, 1967

By F. F. Aplan

Prologue Antoine Marc Gaudin (Fig. 1) was truly a giant in the field of mineral processing, and his shadow is still cast long on our profession. "Tony," as his students affectionately called him (but never to his face), came to the United States in 1917 and enrolled at Columbia University where he studied under Professor Arthur F. Taggart. Later, as a lecturer, he wrote his classic comminution paper (Gaudin, 1926). This important work led to his appointment as an associate professor at The University of Utah, where he conducted highly original work on flotation fundamentals that is still widely quoted today (Gaudin et al., 1928-30). In 1929, he was appointed Research Professor of Ore Dressing at the Montana School of Mines in Butte. Shortly thereafter, he published his first book, Flotation (Gaudin, 1932). Because Gaudin could so quickly cut through the fog to get to the essence of a problem, this is still a valuable reference book. It is a valued part of my personal library, and I consult it frequently. Over the next decade, he conducted an outstanding graduate research program at Butte, but, more importantly, he honed his undergraduate lectures and produced the century's outstanding text in the field, Elements of Mineral Dressing (Gaudin, 1939). More than 50 years later, this terse book is still found to contain most of the elements of the discipline. Its sections on the

Jan 1, 1994

By C. A. Young

Previous experimental results have shown that an increase in temperature and/or oxygen concentration leads to an increase in the hydrophobicity of fluorite (CaF2) with adsorbed oleate. Subsequently, ex-situ Fourier transform infrared (FT-IR) transmission studies suggested that this increase in hydrophobicity was the result of double-bond reactions between adjacent oleate species adsorbed at the fluorite surface. Now an in-situ FT-IR study on single crystals of fluorite has been used to monitor this phenomenon using internal reflection spectroscopy (IRS) with the crystals serving as reactive internal reflection elements. The double-bond reaction has been correlated with in-situ adsorption density measurements. These results demonstrate that only the first chemisorbed oleate layer undergoes the double-bond reaction at an appreciable rate. However, multilayers of precipitated calcium oleate in the case of fluorite appear to react minimally even for oxygen saturated solutions at elevated temperatures.

Jan 1, 1991

By Erik S. Bernard

"INTRODUCTION Conventional steel bar reinforcement is used in many tunnel linings to provide high flexural and tensile load resistance. These Reinforced Concrete (RC) tunnel linings may suffer flexural cracking during service or, in the case of precast concrete segments, during production, handling, or installation. Cracks can lead to corrosion of steel reinforcement, so limits are placed on maximum acceptable crack widths to reduce the likelihood of corrosion during the intended design life (AFTES, 2013; MC2010, 2012). However, the relatively light level of reinforcement used in many applications can result in quite wide in-service crack widths, so either additional steel bar reinforcement is required to limit maximum crack widths, or fibers can be included to control crack widths. Numerous investigations have been undertaken into the efficacy of including steel fibers to reduce crack widths in conventionally reinforced members (Stang and Aarre, 1992; Abrishami and Mitchell, 1997; Bischoff, 2003; Dupont and Vandevalle, 2003; and Jansson et al, 2010), but steel fibers suffer the problem that they are at least as sensitive to corrosion at cracks as steel bars and therefore have similarly tight limits placed on acceptable crack widths (AFTES, 2013). An alternative means of maintaining narrow crack limits in RC members has therefore been sought. The current investigation was instigated following an observation that theories promoted as an explanation for the ability of steel fibers to reduce crack widths in reinforced concrete flexural members (Deluce et al, 2014) do not depend on the material composition of the fibers used but instead depend primarily on the tensile stress generated by the fibers across cracks. Since it is known that macro-synthetic fibers are capable of equaling the post-crack tensile capacity of steel fibers, it has been hypothesized that macro-synthetic fibers are also capable of reducing crack widths in reinforced concrete flexural members but with the added advantage that macro-synthetic fibers are completely immune to the effects of corrosion. Use of macro-synthetic fibers to reduce maximum crack widths in reinforced concrete flexural members subject to aggressive environmental exposure is more rational than use of steel fibers because steel fibers are very sensitive to the corrosive effects of environmental exposure at cracks. The current investigation was therefore undertaken to explore the potential use of macro-synthetic fibers to reduce maximum crack widths in reinforced concrete members subject to flexure. Barchip BC54 fibers were selected as they are one of the most widely used and competitive high performance macro-synthetic fibers currently available."

Jan 1, 2016

By Y. J. Wang

The definitions of system pressure loss (mine head) and system resistance, which are traditionally associated with single-fan net- works, are applied to multiple-fan ventilation networks. The system characteristics -- relations among air power, pressure loss, air quantity and resistance -- are analyzed by introducing the concept of subsystems. These subsystems are associated with the fans located in a cutset of the network. For a multiple-fan network, the resistances for the subsystems and total system are dependent on the quantity ratios of the subsystems. In general the pressure loss of a subsystem or a total system does not vary as the square of the corresponding air quantity. If the quantity ratios of subsystems are all held constant, then the resistances become constant and the pressure losses are predictable from the quantities employing the "square law." The system resistance has a minimum value under the natural- splitting flow pattern. Being independent of the value of system quantity, the minimum system resistance provides a basis for comparing the different networks.

Jan 1, 1983

By Francisco J. Escandon V.

Numerous lead-zinc-barite-fluorite ore deposits, with simple mineralogy and roughly concordant with bedding, are found widely distributed all over the world, having been denominated and well described as "stratiform deposits" or "strata-bound ore bodies", not having any genetic relationship. During several years, its origin has been discussed, without getting to general agreement regarding the main mining districts of this type. Through studies made of large stratiform deposits in the United States, Europe and Russia, it has been found that there are, within this classification, syngenctic diagenetic and epigenetic ore bodies. During the Symposium about the genesis of the stratiform lead-zinc-fluorite-barite deposits, carried out in New York in 1966, Frank G. Snyder (1), presented an excellent analysis of the theories of the origin of these deposits and of the evaluation of the criteria regarding classification. As per his definitions (Table 1), "a deposit is syngenetic if formed by processes similar to and simultaneously with the enclosing rock, epigenetic if introduced into a pre-existing rock and a diagenetic origin implies deposition of metals with the host sediments but with recrystallization, rearrengement and limited migration".

Jan 1, 1974

By Michael Traylor, Michael Jatczak, Brett Robinson

The Detroit River Outfall No. 2. is an effluent water conveyance system linking the Detroit Metropolitan Wastewater Treatment Plant to the Detroit River. The 6.4m (21ft) finished diameter tunnel extends 1,890m (6,200ft) east from the bottom of a 91m(300ft) deep, 9.2m (30ft) diameter drop shaft. At the eastern terminus of the tunnel, six Riser Shafts connect the tunnel to diffuser heads on the riverbed. The tunnel runs through a highly fractured Limestone formation capable of producing high levels of groundwater in?ows and Hydrogen Sul?de gas. Control of this water and gas was a theme which ran through the entire Project’s design and construction. This paper will provide an overview of each portion of the Project’s construction, including the Entrance Shaft, Precast Concrete Segments, TBM Tunnel, Pre-Excavation Grouting Methods, and the Riser Shafts.

Jan 1, 2003

By S. K. Kawatra, S. K. Valluri, S. J. Root

Common carbon dioxide capturing reagents, such as amines and sodium hydroxide, are expensive, toxic, and energy intensive to regenerate. We have added frothers to a sodium carbonate solution in order to increase the surface area available for CO2 transport within the packed bed of a counter current scrubbing column. Addition of frothers has improved the performance of sodium carbonate scrubbing solutions to be on par with sodium hydroxide scrubbing solutions. This novel enhancement of a relatively inexpensive CO2 capture-regeneration cycle shows potential to allow plants to turn a profit by sequestering a waste product. These results are discussed in detail in the following manuscript. INTRODUCTION The combustion of fossil fuels converts chemical energy to thermal energy. CO2 is produced as a byproduct of the reaction. 80% of the world’s electricity is produced by using this thermal energy to power a generator, accounting for 40% of global carbon dioxide emissions. In an effort to stabilize the rising atmospheric CO2 levels, researchers are investigating the application of carbon capture and storage (CCS) systems in power plants. [1] Efforts to capture CO2 at some power plants have been successful, but the cost of installing and operating the required equipment is high. As such, very few power plants have CCS systems. If CO2 can be captured and processed into a product that can be sold at a profit, installing CCS systems in power plants will be a very attractive business decision. In order for the sale of captured CO2 to become a profitable venture, the cost of capturing the CO2 from a flue gas must be reduced. BACKGROUND The most common method for separating CO2 from a flue gas is by passing it through a counter-current packed bed scrubbing column. The flue gas enters the bottom of a column while a solution of a chemical with properties advantageous to the absorption of CO2 is pumped to the top. The fluids interact in a packed bed, where the CO2 is transported from the gas to the liquid. CO2 is an acid gas, so it is common for the scrubbing solution to be alkaline in nature in order to neutralize the carbonic acid that is formed when it is dissolves into water. The exhaust exits the top of the column free of carbon dioxide, which exits the column in the scrubbing solution, reacting or complexing with the absorbent. Figure 1 is a schematic drawing of a CO2 scrubbing column. It shows the molar flowrates and compositions of the gas and liquid at the bottom [1], the top [2], and an arbitrary height in the column [Z]. [2,15] L is the molar flowrate of liquid at any point in in the column. G is the molar flowrate of gas at any point in the column. Since the CO2 is transported from the gas to the liquid, L and G are variable with respect to height. To simplify calculations, the CO2 free molar flowrates Ls and Gs are often used. X is the fraction moles of aqueous CO2 per mole of CO2 free liquid. Y is the fraction moles of gaseous CO2 per mole of CO2 free gas. Figure 2 is a composition diagram of the scrubbing column depicted in figure 1.

Jan 1, 2019

By J. P. De Carvalho, R. Dimitrakopoulos

An actor-critic reinforcement learning approach is presented to improve the production of an industrial mining complex by defining shovel allocation and adapting the short-term plan given grade-control decisions. Blasthole data updates the simulated orebody models, which are input into a stochastic grade-control method based on a spatially constrained clustering approach that minimizes the profit-loss function. These aspects are embedded in a discrete-event simulator that defines the material flow from faces to processors. A case study at a copper mining complex shows the methods’ ability to adapt to new information, improving the quality of the material feed and increasing cash flow by 23% compared to a baseline case.

Jun 25, 2023

By J. C. Motz

The advantages of producing a fine mill feed have been recognized for many years. The extent to which fine crushing can be carried out will vary and depends on the ore characteristics, plant and crusher design. Unfortunately, the ore characteristics are generally beyond our control, so the concentration of effort lies primarily on the plant arrangement, equipment design and operation Where fine crushing should stop and grinding begin is controversial and is influenced greatly by personal opinions and experiences. Often, this break point will be different if consideration is being given to a new plant in comparison to a modest expansion. Most new plant designs employ the largest and most efficient equipment. The modification of existing plants becomes more complex because of the space requirements and the related equipment already in operation. Fine crushing is, of course, a relative term. Obtaining a final crusher product of minus 3/4" is commonplace today and can occasionally be obtained in an open circuit final crushing stage.

Jan 1, 1980

By Trevor R. Ellis

In this paper a method is presented for estimating the specifications of sandstone-type uranium deposits which will be the minimum that can meet a company's economic requirements for investment. The method interpolates and extrapolates from available cost data for typical mines to provide the costs for a wide range of possible deposits. The range of deposits achieving the company's required discounted cash flow rate of return on investment at an estimated uranium oxide selling price is then calculated, thus giving the complete range of deposits which meet the minimum required specifications. Prospects are then evaluated by comparison with these minimum requirements.

Jan 1, 1979

By Robert L. Somerville

As more phosphate deposits are discovered and new mines are developed, the necessity of critically evaluating various rocks for phosphoric acid production recurs ever more frequently. This need is accentuated by the increasing number of, fertilizer plants being constructed on deep water at various locations to serve world markets and to take advantage of locally-available sulfur or sulfur-bearing ores. A major proportion of all phosphate rock mined is consumed by wet-process plants and this acid in turn is consumed, usually captively, in the manufacture of fertilizer. It is apparent, therefore, that the first question asked by the developer of a new deposit is - How will it work in a wet-process plant? and conversely, when developing a deep water, project, one of the early studies required is - Which of the available rocks shall we use? What is the correct price to pay? How do we compare one rock with another? The economic importance of even minor aspects of these questions

Jan 1, 1966

By P. Mendoza, R. Siwale, H. Amini, R. Silva, M. Richards, V. Ngcoza, D. Rivera, C. Canaza, R. van Reenen

Development of a realistic flotation model to predict its performance is of paramount importance to the processing plant and operators, a model that accounts for predictive and no-predictive maintenance simulating individual equipment downtime and the effect of it in the metallurgical performance on the flotation bank with final recoveries and grades has a huge advantage on optimizing the flotation circuit/bank in terms of mechanical and metallurgical side. The Model was developed in a dynamic environment that allows for a better and more realistic simulation of the flotation bank. The maintenance model accounts for the Failure rate, Mean Time Between Failures (MTBF), Mean Time to Failure (MTTF) and Reliability (R(t)) those characteristics are combined to a multi-compartment process model that consists of a slurry recovery model, two options of froth recovery models, entrainment and carry capacity as a final check for the system. In addition to the maintenance and process model, a dynamic dart valve model was added to the simulation in order to have a realistic model to control the slurry level at the flotation cell. The paper goes over a study case for a current flotation operation trying to explore all the elements and the simulator to optimize the Rougher flotation bank.

Mar 2, 2022

By Karl A. Olsson

The Glenharold Mine is a surface mine operated by Consolidation Coal Company. The mine is located approximately 90 kilometers (55 miles) northwest of Bismarck, and 3 kilometers (2 miles) southeast of Stanton in west central North Dakota. Glenharold has a nominal design capacity of 3.0 million metric tons per year (3.3 million short tons per year). With the exception of local coal sales, this production supplies fuel for Basin Electric's Leland Olds generating station, a mine mouth power plant. The mine has 175 hourly and 50 salary employees. The Glenharold reserve extends over 210 square kilometers (80 square miles). The mining area is on a dissected plateau between the broad flat Missouri River flood plain to the north and the gently rolling uplands to the south. Erosion by intermittently flowing streams has produced many narrow, steep-walled, drainage ways. Mining begins at the 6 meter (20 foot) cover line and continues to the economic recovery line.

Jan 1, 1982

By B. A. Hancock

New permit discharge standards instituted at Hecla Limited?s Lucky Friday Mine required installation of water treatment plants to manage water quality at two outfalls to the South Fork of the Coeur d?Alene River. The 002 Outfall Water Treatment Plant (WTP) is a clarification-filtration plant for treating the combined mill and underground discharge water flows. Process optimization efforts were a significant challenge until the negative impact the exploration diamond drilling products had on the clarification process was identified and resolved. The products were being wasted directly to the mine water discharge system which was pumped to the surface WTP. Anionic soluble oil and polyacrylamide based products were causing TSS particle hydrophobicity and dispersion that greatly affected coagulation and flocculation response, resulting in excessive chemical usage and treatment control issues. This paper details how problems associated with the drill products negatively impacted the 002 WTP and how system changes, alternative product usage and treatment at the source resulted in more consistent plant performance.

Jan 1, 2011

By B. K. Baird

The application of cutoffs during and after pit optimization is examined for a lower-grade multi-metallic copper deposit. Pit optimization requires calculation of the net revenue associated with each mining block, incorporating parameters such as metal prices, grades and expected recoveries, mining and processing costs, smelting and refining charges, and penalty element and royalty charges. Sensitivity analysis during pit optimization reveals which of these parameters have a significant effect on the total contained resource tonnage and total contained non-discounted revenue in the optimized pit. The cumulative effect of changing several of the more significant parameters is investigated. Application of a copper cutoff grade to a block inside the optimized pit could result in the less than optimal extraction of the resource. A block with copper grade below the applied cutoff could be economic due to the presence of other metals. Conversely, a higher copper grade block may be sub-economic. The relative merits of applying a copper grade cutoff, "equivalent grade" cutoff and dollar value per ton cutoff to blocks inside the optimum pit are discussed.

Jan 1, 1999

By Robert C. Meaders

In this paper, autogenous grinding is defined as the combined crushing and grinder of a run-of-mine ore or the product from a primary crusher, in a single stage grinding mill. This is in contrast to pebble milling where pebbles are substituted for steel balls to grind a ball mill size feed. The autogenous mill to compete in efficiency with normal methods of crushing and grinding must not use greater power, must use less labor and steel, and must produce an equivalent product.

Jan 1, 1963

By Klaus Beckmann

Gentlemen : My object reads "Longwall Rapid Advance of Coal Mining in the Federal Republic of Germany". It is true that the percentage of coal obtained in your country from longwall faces, with at present 1.2, is still rather low, but it increased considerably since 1966 with 0.4 %. The coal mines of the Federal Republic of Germany ever used longwall as the classical method of coal getting. All attempts to introduce bord and pillar mining did not lead to any wider application of this method. The principal reasons, for this appear to have been: - the deeper depth of our workings, - the wish to keep working losses as low as possible and to utilize the deposits opened up by deep and therefore expensive shafts to the furthest possible degree, - the dense sequence of seams and the mutual influencing of the working points, - the high number of disturbances in the geologically much stressed deposits, - and the necessary considerations to the protection of the densely built-upon surface.

Jan 1, 1970